Motorists heading over the Sierra are advised to travel Wednesday morning or wait until Sunday.
A cold winter storm due to arrive late Wednesday afternoon will bring heavy snow, making travel through the mountains "very difficult to impossible", according to the National Weather Service, which has issued a winter storm warning effective from 4 p.m. Wednesday to 10 p.m. Saturday.
Between 60 and 80 inches of snow are forecast for the Sierra passes over the next four days, said Cory Mueller, a meteorologist with the National Weather Service. The Sacramento area is expected to receive 1 to 2 inches or rain over the same period.
What is unusual about this storm is the forecast for snow at low elevations that rarely see more than a dusting. This will make travel particularly difficult on Interstate 80 and Highway 50, Mueller said. Instead of chain restrictions and highway closures between Blue Canyon or Echo Summit and the Nevada state line, those conditions likely will extend as far as Applegate in Placer County and to just east of Placerville in El Dorado County, he said.
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Colfax could receive 4 to 6 inches of snow over the four-day period, with 12 to 18 inches forecast for the Camino area. Placerville and Applegate could see an inch of snow.
The heaviest impacts in terms of snow in the mountains and rain in the valley are expected Wednesday night through Friday. In the Sacramento area, the forecast includes possible thunderstorms Thursday.
The National Weather Service has issued an avalanche warning for the back country, including areas around Lake Tahoe, due to heavy snow and wind.
Mueller said temperatures in the Sacramento region are expected to be too warm for snow. Daytime highs in the mid-40s to low 50s are forecast, with overnight lows in the upper 30s.